Developing an accurate second language competence different from the mother tongue has become an essential skill in today's globalized world, and therefore it is a highly valued and demanded learning among the main educational institutions and models. However, it is a complex process that is influenced by numerous and, in many cases, unknown factors, which are not usually taken into consideration when designing second language learning processes, which tend to lead to inadequate teaching and may lead to school failure that could have been avoided.

216 in-service teachers from all non-university educational stages of the Community of Madrid, Spain, evaluate the significance of 44 factors traditionally associated with second language learning, which are grouped into four general categories (factors linked to students; factors linked to teachers; learning structure and organisation; and learning environment) through a five-point Likert scale.

The data were collected using a Google Forms questionnaire through the research described in Arigita-García et al. (2021). The sample is heterogeneous concerning different attribute variables such as age, teaching experience, gender, school ownership, and the language in which classes are taught. The sample was obtained through social networks and teacher forums.

The data collection offers essential information to better understand the process of second language learning, as it gathers the experience and learning accumulated by the teachers who took part in this work, which implies direct information from the educational reality that they are intended to improve.

Computerized questionnaire through the Google Forms private server

An individual and anonymous online questionnaire to 216 teachers describing the significance of 44 factors when learning a second language on a five-point Likert scale.